Lookup-table-based green imbalance correction system and method

Abstract

In a lookup-table-based green imbalance correction system and method, an image sensor with a color filter array placed thereover outputs raw data. A green imbalance correction device corrects the raw data according to a lookup table stored in a memory, thereby resulting in corrected raw data. A color interpolation device receives the corrected raw data to result in full-color data.

What is claimed is: 
     
         1 . A lookup-table-based green imbalance correction system, comprising:
 an image sensor with a color filter array placed over the image sensor configured to output raw data;   a memory configured to store a lookup table;   a green imbalance correction device configured to correct the raw data according to the lookup table, thereby resulting in corrected raw data; and   a color interpolation device coupled to receive the corrected raw data to result in full-color data.   
     
     
         2 . The system of  claim 1 , wherein the color filter array comprises a Bayer color filter array. 
     
     
         3 . The system of  claim 1 , further comprising an image signal processor that encompasses the green imbalance correction device and/or the color interpolation device; or controls operations of the green imbalance correction device and/or the color interpolation device. 
     
     
         4 . The system of  claim 1 , wherein a current green pixel of the raw data to be currently processed within a process mask to result in a corrected current green pixel is expressed as summation of weighted neighboring green pixels and the current green pixel before being processed, weights associated with the neighboring green pixels within the process mask being looked up from the lookup table. 
     
     
         5 . The system of  claim 4 , wherein the weights associated with the neighboring green pixels are determined according to their differences with the current green pixel, respectively. 
     
     
         6 . The system of  claim 5 , wherein the larger the difference is, the lower the weight is, and vice versa. 
     
     
         7 . The system of  claim 6 , wherein the weight associated with the neighboring green pixel is determined in the following steps:
 obtaining a difference between the neighboring green pixel and a current green pixel;   comparing the difference with a predetermined difference threshold;   subdividing the predetermined difference threshold into sections;   determining a section into which the obtained difference is located, thereby determining an index associated with the section where the obtained difference is located; and   obtaining a corresponding weight from the lookup table according to the index.   
     
     
         8 . The system of  claim 4 , wherein the corrected current green pixel is further adjusted by a strength, the strength being dependent on a location of the process mask within an image made of the raw data. 
     
     
         9 . The system of  claim 8 , wherein the strength is determined according to a distance between a center of the process mask and a prime point of the image made of the raw data. 
     
     
         10 . The system of  claim 9 , wherein the larger the distance is, the larger the strength is, and vice versa. 
     
     
         11 . A lookup-table-based green imbalance correction method, comprising:
 outputting raw data from an image sensor with a color filter array placed over the image sensor;   correcting the raw data according to a lookup table to result in corrected raw data rendered with substantially reduced amount in green imbalance; and   color interpolating the corrected raw data to result in full-color data.   
     
     
         12 . The method of  claim 11 , wherein the color filter array comprises a Bayer color filter array. 
     
     
         13 . The method of  claim 11 , wherein correcting step and/or the color interpolating step is performed or controlled by an image signal processor. 
     
     
         14 . The method of  claim 11 , wherein a current green pixel of the raw data to be currently processed within a process mask to result in a corrected current green pixel is expressed as summation of weighted neighboring green pixels and the current green pixel before being processed, weights associated with the neighboring green pixels within the process mask being looked up from the lookup table. 
     
     
         15 . The method of  claim 14 , wherein the weights associated with the neighboring green pixels are determined according to their differences with the current green pixel, respectively. 
     
     
         16 . The method of  claim 15 , wherein the larger the difference is, the lower the weight is, and vice versa. 
     
     
         17 . The method of  claim 16 , wherein the weight associated with the neighboring green pixel is determined in the following steps:
 obtaining a difference between the neighboring green pixel and a current green pixel;   comparing the difference with a predetermined difference threshold;   subdividing the predetermined difference threshold into sections;   determining a section into which the obtained difference is located, thereby determining an index associated with the section where the obtained difference is located; and   obtaining a corresponding weight from the lookup table according to the index.   
     
     
         18 . The method of  claim 14 , wherein the corrected current green pixel is further adjusted by a strength, the strength being dependent on a location of the process mask within an image made of the raw data. 
     
     
         19 . The method of  claim 18 , wherein the strength is determined according to a distance between a center of the process mask and a prime point of the image made of the raw data. 
     
     
         20 . The method of  claim 19 , wherein the larger the distance is, the larger the strength is, and vice versa.